One presently known type of undercarpet cable system includes a flat multiconductor cable which is assembled between a plastic shield and a metallic shield. The cable assembly, comprising the cable and its two protective shields, is installed between a floor and overlying carpeting. The multiconductor cable includes a plurality of flat electrical conductors which are contained in a casing comprised of a thin sheet of electrical insulation. The plastic shield provides a cushion for the multiconductor cable so as to resist the abrasion and possible piercing of the cable insulation by projections extending upwardly from the floor, such projections being especially prevalent if the floor is made of concrete or a similar coarse building material. The metallic shield resists piercing of the cable insulation by an object inserted through the carpet. By electrically grounding the metallic shield, any electrically conductive object which may pierce the metallic shield and contact a "hot", i.e., electrically energized, conductor of the multiconductor cable will be grounded so as to protect a person who contacts the object from electrical hazard.
Inasmuch as the multiconductor cable and the two shields may not be positively attached to each other either before, during or after their installation, there is the possibility that the cable could be installed without the shields or that, once installed, the shields could move relative to the cable, thereby leaving a portion of the cable exposed either aside the metallic shield or the plastic shield. Such exposed cable runs a greater risk of being pierced than a properly covered cable and, therefore, presents an electrical hazard.
Where the metallic shield is properly positioned above the cable, there remains the possibility that the metallic shield will not be properly grounded, for instance, by failure to electrically connect it to ground. Like a properly grounded shield which is improperly installed so as to expose a portion of the cable, a cable having a nongrounded metallic shield presents a potentially hazardous situation.
Such known undercarpet wiring system includes a network of cable assemblies, the individual cable assemblies being electrically connected. In such a system, the metallic shield of each assembly is grounded by use of connectors for electrical connection of adjoining metallic shields. In such arrangement, shield grounding integrity is dependent on physical continuity of the shield. Thus, if the shield is interrupted as by cutting, the free remnant of the shield will not be electrically continuous to ground, with resulting hazard.
The formation of cable networks may require changes in the running direction of the cable assembly. The shields and cable of each cable assembly have not heretofore been collectively and simultaneously folded since known folding practice causes a reversal of the positions of the shields with respect to the cable, i.e., prior to folding the metallic shield would be above the cable and the plastic shield would be below the cable but, as a result of folding, the metallic shield would be below the cable and the plastic shield would be above the cable. Such a reversal in the relative positions of the shields is obviously undesirable.
For maintaining the metallic shield above the cable in the past, the direction of the cable assembly has been changed by folding the lower plastic shield along a predetermined bend line, folding the multiconductor cable along substantially the same bend line as the lower plastic shield, and then stacking the folded cable on top of the folded plastic shield. After folding the metallic shield along substantially the same bend line as the plastic shield and the cable, the folded metallic shield was stacked on top of the folded cable.
The bending and stacking technique described above suffers from several problems. First, inasmuch as the plastic shield, multiconductor cable, and metallic shield are not directly connected to each other, a slight difference in the bending line of any one of them will complicate the proper vertical alignment of the cable with at least one of the shields after the change of direction has been made in the cable assembly. Second, stacking the bent portions of the shields and cable on top of each other increases the profile of the cable assembly in the vicinity of the bend lines, thereby resulting in the possible formation of a lump in the overlying carpet. Moveover, such stacking is often difficult to achieve due to the tendency of loops formed in the shields and cable at the bend lines to slip on each other. Third, conductors which lie to the side of the medial longitudinal axis of the cable, undergo a reversal in position relative to the medial longitudinal axis of the cable, i.e., go from left to right thereof as a result of such folding. Such change may confuse an installer and give rise to error, particularly where termination apparatus at opposite ends of a folded cable assembly have commonly polarized terminals. Finally, any folding technique requires that the cable assembly be handled manually by an installer. Inasmuch as the edges of the cable and shields are very thin and relatively rigid, there is a risk that they will cut the installer, and known efforts have not sought to diminish such hazard.